1. Field of the Invention
This invention relates to a vulcanizing accelerator, more particularly a vulcanization accelerator having no adverse effect on polyester fibre used as a reinforcing agent for rubber.
2. Description of the Prior Art
In rubber products such as tires, belts, hoses and the like, fibres such as polyester, nylon, rayon and the like have heretofore been used as reinforcing materials. Among them, polyester resins have a high modulus of elasticity and an excellent dimentional stability, therefore in recent years, the demand for rubber products using polyester fibers has increased.
In vulcanizing a rubber, in particular, a lower unsaturated rubber having a small number of double bonds such as isobutylene-isoprene rubber or the like by using polyester fiber, there has heretofore been generally used a method using as a vulcanization accelerator a thiuram derivative such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetramethylthiuram monosulfide or the like because it is advantageous, for example, in that the vulcanization rate is rapid and that the vulcanization density of the product obtained is high.
However, although the conventional thiuram type vulcanization accelerators have such advantages, they have a great disadvantage in that they deteriorate polyester fibres and lower their strength, and they have been strongly desired to be improved in this point (Journal of The Society of Rubber Industry, Japan, Vol. 54, No. 2, p. 123).